This invention is related to the field of organometal compound catalysts.
The production of polymers is a multi-billion dollar business. This business produces billions of pounds of polymers each year. Millions of dollars have been spent on developing technologies that can add value to this business.
One of these technologies is called metallocene catalyst technology. Metallocene catalysts have been known since about 1958. However, their low productivity did not allow them to be commercialized. About 1975, it was discovered that contacting one part water with one part trimethylaluminum to form methyl aluminoxane, and then contacting such methyl aluminoxane with a metallocene compound, formed a metallocene catalyst that had greater activity. However, it was soon realized that large amounts of expensive methyl aluminoxane were needed to form an active metallocene catalyst. This has been a significant impediment to the commercialization of metallocene catalysts.
Fluoro-organo borate compounds have been use in place of large amounts of methyl aluminoxane. However, this is not satisfactory, since such borate compounds are very sensitive to poisons and decomposition, and can also be very expensive.
It should also be noted that having a heterogeneous catalyst is important. This is because heterogeneous catalysts are required for most modern commercial polymerization processes. Furthermore, heterogeneous catalysts can lead to the formation of substantially uniform polymer particles that have a high bulk density. These types of substantially uniformed particles are desirable because they improve the efficiency of polymer production and transportation. Efforts have been made to produce heterogeneous metallocene catalysts; however, these catalysts have not been entirely satisfactory.
Therefore, the inventors provide this invention to help solve these problems.
An object of this invention is to provide a process that produces a catalyst composition that can be used to polymerize at least one monomer to produce a polymer.
Another object of this invention is to provide the catalyst composition.
Another object of this invention is to provide a process comprising contacting at least one monomer and the catalyst composition under polymerization conditions to produce the polymer.
Another object of this invention is to provide an article that comprises the polymer produced with the catalyst composition of this invention.
In accordance with one embodiment of this invention, a process to produce a catalyst composition is provided. The process comprises (or optionally, xe2x80x9cconsists essentially ofxe2x80x9d, or xe2x80x9cconsists ofxe2x80x9d) contacting an organometal compound, an organoaluminum compound, and a treated solid oxide compound to produce the catalyst composition,
wherein the organometal compound has the following general formula:
(X1)(X2)(X3)(X4)M1
wherein M1 is selected from the group consisting of titanium, zirconium, and hafnium;
wherein (X1) is independently selected from the group consisting of cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls;
wherein substituents on the substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls of (X1) are selected from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen;
wherein at least one substituent on (X1) can be a bridging group which connects (X1) and (X2);
wherein (X3) and (X4) are independently selected from the group consisting of halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic groups and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups;
wherein (X2) is selected from the group consisting of cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, substituted fluorenyls, halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic groups and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups;
wherein substituents on (X2) are selected from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic groups and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen;
wherein at least one substituent on (X2) can be a bridging group which connects (X1) and (X2);
wherein the organoaluminum compound has the following general formula:
Al(X5)n(X6)3xe2x88x92n
wherein (X5) is a hydrocarbyl having from 1-20 carbon atoms;
wherein (X6) is a halide, hydride, or alkoxide;
wherein xe2x80x9cnxe2x80x9d is a number from 1 to 3 inclusive; and
wherein the treated solid oxide compound comprises at least one halogen, zirconium, and a solid oxide compound;
wherein the halogen is at least one selected from the group consisting of chlorine, bromine, and fluorine;
wherein the solid oxide compound is selected from the group consisting of alumina, aluminophosphate, aluminosilicate, and mixtures thereof
In accordance with another embodiment of this invention, a process is provided comprising contacting at least one monomer and the catalyst composition under polymerization conditions to produce a polymer.
In accordance with another embodiment of this invention, an article is provided. The article comprises the polymer produced in accordance with this invention.
These objects, and other objects, will become more apparent to those with ordinary skill in the art after reading this disclosure.
Organometal compounds used in this invention have the following general formula:
(X1)(X2)(X3)(X4)M1
In this formula, M1 is selected from the group consisting of titanium, zirconium, and hafnium. Currently, it is most preferred when M1 is zirconium.
In this formula, (X1) is independently selected from the group consisting of (hereafter xe2x80x9cGroup OMC-Ixe2x80x9d) cyclopentadienyls, indenyls, fluorenyls, substituted cyclopentadienyls, substituted indenyls, such as, for example, tetrahydroindenyls, and substituted fluorenyls, such as, for example, octahydrofluorenyls.
Substituents on the substituted cyclopentadienyls, substituted indenyls, and substituted fluorenyls of (X1) can be selected independently from the group consisting of aliphatic groups, cyclic groups, combinations of aliphatic and cyclic groups, silyl groups, alkyl halide groups, halides, organometallic groups, phosphorus groups, nitrogen groups, silicon, phosphorus, boron, germanium, and hydrogen, as long as these groups do not substantially, and adversely, affect the polymerization activity of the catalyst composition.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffins and olefins. Suitable examples of cyclic groups are cycloparaffins, cycloolefins, cycloacetylenes, and arenes. Substituted silyl groups include, but are not limited to, alkylsilyl groups where each alkyl group contains from 1 to about 12 carbon atoms, arylsilyl groups, and arylalkylsilyl groups. Suitable alkyl halide groups have alkyl groups with 1 to about 12 carbon atoms. Suitable organometallic groups include, but are not limited to, substituted silyl derivatives, substituted tin groups, substituted germanium groups, and substituted boron groups.
Suitable examples of such substituents are methyl, ethyl, propyl, butyl, tert-butyl, isobutyl, amyl, isoamyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, dodecyl, 2-ethylhexyl, pentenyl, butenyl, phenyl, chloro, bromo, iodo, trimethylsilyl, and phenyloctylsilyl.
In this formula, (X3) and (X4) are independently selected from the group consisting of (hereafter xe2x80x9cGroup OMC-IIxe2x80x9d) halides, aliphatic groups, substituted aliphatic groups, cyclic groups, substituted cyclic groups, combinations of aliphatic groups and cyclic groups, combinations of substituted aliphatic groups and cyclic groups, combinations of aliphatic groups and substituted cyclic groups, combinations of substituted aliphatic and substituted cyclic groups, amido groups, substituted amido groups, phosphido groups, substituted phosphido groups, alkyloxide groups, substituted alkyloxide groups, aryloxide groups, substituted aryloxide groups, organometallic groups, and substituted organometallic groups, as long as these groups do not substantially, and adversely, affect the polymerization activity of the catalyst composition.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffins and olefins. Suitable examples of cyclic groups are cycloparaffins, cycloolefins, cycloacetylenes, and arenes. Currently, it is preferred when (X3) and (X4) are selected from the group consisting of halides and hydrocarbyls, where such hydrocarbyls have from 1 to about 10 carbon atoms. However, it is most preferred when (X3) and (X4) are selected from the group consisting of fluoro, chloro, and methyl.
In this formula, (X2) can be selected from either Group OMC-I or Group OMC-II.
At least one substituent on (X1) or (X2) can be a bridging group that connects (X1) and (X2), as long as the bridging group does not substantially, and adversely, affect the activity of the catalyst composition. Suitable bridging groups include, but are not limited to, aliphatic groups, cyclic groups, combinations of aliphatic groups and cyclic groups, phosphorous groups, nitrogen groups, organometallic groups, silicon, phosphorus, boron, and germanium.
Suitable examples of aliphatic groups are hydrocarbyls, such as, for example, paraffins and olefins. Suitable examples of cyclic groups are cycloparaffins, cycloolefins, cycloacetylenes, and arenes. Suitable organometallic groups include, but are not limited to, substituted silyl derivatives, substituted tin groups, substituted germanium groups, and substituted boron groups.
Various processes are known to make these organometal compounds. See, for example, U.S. Pat. Nos. 4,939,217; 5,210,352; 5,436,305; 5,401,817; 5,631,335, 5,571,880; 5,191,132; 5,480,848; 5,399,636; 5,565,592; 5,347,026; 5,594,078; 5,498,581; 5,496,781; 5,563,284; 5,554,795; 5,420,320; 5,451,649; 5,541,272; 5,705,478; 5,631,203; 5,654,454; 5,705,579; and 5,668,230; the entire disclosures of which are hereby incorporated by reference.
Specific examples of such organometal compounds are as follows: bis(cyclopentadienyl)hafnium dichloride; 
bis(cyclopentadienyl)zirconium dichloride; 
1,2-ethanediylbis(xcex75-1-indenyl)di-n-butoxyhafnium; 
1,2-ethanediylbis(xcex75-1-indenyl)dimethylzirconium; 
3,3-pentanediylbis(xcex75-4,5,6,7-tetrahydro-1-indenyl)hafnium dichloride; 
methylphenylsilylbis(xcex75-4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride; 
bis(n-butylcyclopentadienyl)di-t-butylamidohafnium; 
bis(n-butylcyclopentadienyl)zirconium dichloride; 
dimethylsilylbis(1-indenyl)zirconium dichloride; 
nonyl(phenyl)silylbis(1-indenyl)hafnium dichloride; 
dimethylsilylbis(xcex75-4,5,6,7-tetrahydro-1-indenyl)zirconium dichloride; 
dimethylsilylbis(2-methyl-1-indenyl)zirconium dichloride; 
1,2-ethanediylbis(9-fluorenyl)zirconium dichloride; 
indenyl diethoxy titanium(IV) chloride; 
(isopropylamidodimethylsilyl)cyclopentadienyltitanium dichloride; 
bis(pentamethylcyclopentadienyl)zirconium dichloride; 
bis(indenyl) zirconium dichloride; 
methyloctylsilyl bis (9-fluorenyl) zirconium dichloride; 
bis-[1-(N,N-diisopropylamino)boratabenzene]hydridozirconium trifluoromethylsulfonate 
Preferably, the organometal compound is selected from the group consisting of
bis(n-butylcyclopentadienyl)zirconium dichloride; 
bis(indenyl)zirconium dichloride; 
dimethylsilylbis(1-indenyl) zirconium dichloride; 
and
methyloctylsilylbis(9-fluorenyl)zirconium dichloride 
Organoaluminum compounds have the following general formula:
Al(X5)n(X6)3xe2x88x92n
In this formula, (X5) is a hydrocarbyl having from 1 to about 20 carbon atoms. Currently, it is preferred when (X5) is an alkyl having from 1 to about 10 carbon atoms. However, it is most preferred when (X5) is selected from the group consisting of methyl, ethyl, propyl, butyl, and isobutyl.
In this formula, (X6) is a halide, hydride, or alkoxide. Currently, it is preferred when (X6) is independently selected from the group consisting of fluoro and chloro. However, it is most preferred when (X6) is chloro.
In this formula, xe2x80x9cnxe2x80x9d is a number from 1 to 3 inclusive. However, it is preferred when xe2x80x9cnxe2x80x9d is 3.
Examples of such compounds are as follows:
trimethylaluminum;
triethylaluminum (TEA);
tripropylaluminum;
diethylaluminum ethoxide;
tributylaluminum;
diisobutylaluminum hydride;
trisobutylaluminum hydride;
trisobutylaluminum; and
diethylaluminum chloride.
Currently, TEA is preferred.
The treated solid oxide compound comprises at least one halogen, zirconium, and a solid oxide compound. The halogen is at least one selected from the group consisting of chlorine, bromine, and fluorine. Generally, the solid oxide compound is selected from the group consisting of alumina, silica, aluminophosphate, aluminosilicate, and mixtures thereof Preferably, the solid oxide compound is alumina. The solid oxide compound can be produced by any method known in the art, such as, for example, by gelling, co-gelling, impregnation of one compound onto another, and flame hydrolysis.
Generally, the surface area of the solid oxide compound after calcining at 500xc2x0 C. is from about 100 to about 1000 m2/g, preferably, from about 200 to about 800 m2/g, and most preferably, from 250 to 600 m2/g.
The pore volume of the solid oxide compound is typically greater than about 0.5 cc/g, preferably, greater than about 0.8 cc/g, and most preferably, greater than 1.0 cc/g.
To produce the treated solid oxide compound, at least one zirconium-containing compound is contacted with the solid oxide compound by any means known in the art to produce a zirconium-containing solid oxide compound. The zirconium can be added to the solid oxide compound before calcining or in a separate step after calcining the solid oxide compound.
Generally, the solid oxide compound is contacted with an aqueous or organic solution of the zirconium-containing compound before calcining. For example, the zirconium can be added to the solid oxide compound by forming a slurry of the solid oxide compound in a solution of the zirconium-containing compound and a suitable solvent such as alcohol or water. Particularly suitable are one to three carbon atom alcohols because of their volatility and low surface tension. A suitable amount of the solution is utilized to provide the desired concentration of zirconium after drying. Any water soluble or organic soluble zirconium compound is suitable that can impregnate the solid oxide compound with zirconium. Examples include, but are not limited to, zirconium tetrapropoxide, zirconyl nitrate, zirconium acetylacetonate, and mixtures thereof. Drying can be effected by any method known in the art. For example, said drying can be completed by suction filtration followed by evaporation, vacuum drying, spray drying, or flash drying.
If the zirconium is added after calcination, one preferred method is to impregnate the solid oxide compound with a hydrocarbon solution of a zirconium-containing compound, preferably a zirconium alkoxide or halide, such as, for example, ZrCl4, Zr(OR)4, and the like, where R is an alkyl or aryl group having 1 to about 12 carbons. Examples of the zirconium alkoxide include, but are not limited to, zirconium tetrapropoxide, zirconium tetrabutoxide, and the
Generally, the amount of zirconium present in the zirconium-containing solid oxide compound is in a range of about 0.1 to about 30 weight percent zirconium where the weight percent is based on the weight of the zirconium-containing solid oxide compound before calcining or the amount added to a precalcined solid oxide compound. Preferably, the amount of zirconium present in the zirconium-containing solid oxide compound is in a range of about 0.5 to about 20 weight percent zirconium based on the weight of the zirconium-containing solid oxide compound before calcining or the amount added to a precalcined solid oxide compound. Most preferably, the amount of zirconium present in the zirconium-containing solid oxide compound is in a range of 1 to 10 weight percent zirconium based on the weight of the zirconium-containing solid oxide compound before calcining or the amount added to a precalcined solid oxide compound.
Before or after the solid oxide compound is combined with the zirconium-containing compound to produce the zirconium-containing solid oxide compound, it is calcined for about 1 minute to about 100 hours, preferably from about 1 hour to about 50 hours, and most preferably, from 3 to 20 hours. Generally, the calcining is conducted at a temperature in a range of about 200xc2x0 C. to about 900xc2x0 C., preferably from about 300xc2x0 C. to about 700xc2x0 C., and most preferably, from 350xc2x0 C. to 600xc2x0 C. The calcining can be conducted in any suitable atmosphere. Generally, the calcining can be completed in an inert atmosphere. Alternatively, the calcining can be completed in an oxidizing atmosphere, such as, oxygen or air, or a reducing atmosphere, such as, hydrogen or carbon monoxide.
After or during calcining, the zirconium-containing solid oxide compound is contacted with at least one halogen-containing compound. The halogen-containing compound is selected from the group consisting of chlorine-containing compounds, bromine-containing compounds, and fluorine-containing compounds. The halogen-containing compound can be in a liquid phase, or preferably, a vapor phase. Optionally, the solid oxide compound can be calcined at 100 to 900xc2x0 C. before being contacted with the halogen-containing compound.
Any method known in the art of contacting the solid oxide compound with the fluorine-containing compound can be used in this invention. A common method is to impregnate the solid oxide compound with an aqueous solution of a fluoride-containing salt before calcining, such as ammonium fluoride [NH4F], ammonium bifluoride [NH4HF2], hydrofluoric acid [HF], ammonium silicofluoride [(H4)2SiF6], ammonium fluoroborate [NH4BF4], ammonium fluorophosphate [NH4PF6], and mixtures thereof.
In a second method, the fluorine-containing compound can be dissolved into an organic compound, such as an alcohol, and added to the solid oxide compound to minimize shrinkage of pores during drying. Drying can be accomplished by an method known in the art, such as, for example, vacuum drying, spray drying, flashing drying, and the like.
In a third method, the fluorine-containing compound can be added during the calcining step. In this technique, the fluorine-containing compound is vaporized into the gas stream used to fluidize the solid oxide compound so that it is fluorided from the gas phase. In addition to some of the fluorine-containing compounds described previously, volatile organic fluorides may be used at temperatures above their decomposition points, or at temperatures high enough to cause reaction. For example, perfluorohexane, perfluorobenzene, trifluoroacetic acid, trifluoroacetic anhydride, hexafluoroacetylacetonate, and mixtures thereof can be vaporized and contacted with the solid oxide compound at about 300 to about 600xc2x0 C. in air or nitrogen. Inorganic fluorine-containing compounds can also be used, such as hydrogen fluoride or even elemental fluorine.
The amount of fluorine on the treated solid oxide compound is about 2 to about 50 weight percent fluorine based on the weight of the treated solid oxide compound before calcining or the amount added to a precalcined solid oxide compound. Preferably, it is about 3 to about 25 weight percent, and most preferably, it is 4 to 20 weight percent fluorine based on the weight of the treated solid oxide compound before calcining or the amount added to a precalcined solid oxide compound.
Any method known in the art of contacting the solid oxide compound with the chlorine-containing compound or bromine-containing compound can be used in this invention. Generally, the contacting is conducted during or after calcining, preferably during calcining. Any suitable chlorine-containing compound or bromine-containing compound that can deposit chlorine or bromine or both on the solid oxide compound can be used. Suitable chlorine-containing compounds and bromine-containing compound include volatile or liquid organic chloride or bromide compounds and inorganic chloride or bromide compounds. Organic chloride or bromide compounds can be selected from the group consisting of carbon tetrachloride, chloroform, dichloroethane, hexachlorobenzene, trichloroacetic acid, bromoform, dibromomethane, perbromopropane, phosgene, and mixtures thereof. Inorganic chloride or bromide compounds can be selected from the group consisting of gaseous hydrogen chloride, silicon tetrachloride, tin tetrachloride, titanium tetrachloride, aluminum trichloride, boron trichloride, thionyl chloride, sulfuryl chloride, hydrogen bromide, boron tribromide, silicon tetrabromide, and mixtures thereof. Additionally, chlorine and bromine gas can be used. Optionally, a fluorine-containing compound can also be included when contacting the zirconium-containing solid oxide compound with the chlorine-containing compound or bromine-containing compound to achieve higher activity in some cases.
If an inorganic chlorine-containing compound or bromine-containing compound is used, such as titanium tetrachloride, aluminum trichloride, or boron trichloride, it also can be possible to contact the chlorine-containing compound or bromine-containing compound with the zirconium-containing solid oxide compound after calcining, either by vapor phase deposition or even by using an anhydrous solvent.
The amount of chlorine or bromine used is from about 0.01 to about 10 times the weight of the treated solid oxide compound before calcining or the amount added to a precalcined solid oxide compound, preferably it is from about 0.05 to about 5 times, most preferably from 0.05 to 1 times the weight of the treated solid oxide compound before calcining or the amount added to a precalcined solid oxide compound.
In another embodiment of this invention, an additional metal other than zirconium can be added to the treated solid oxide compound to enhance the activity of the organometal compound. For example, a metal, such as, zinc, silver, copper, antimony, gallium, tin, nickel, tungsten, and mixtures thereof, can be added. This is especially useful if the solid oxide compound is to be chlorided during calcining.
The catalyst compositions of this invention can be produced by contacting the organometal compound, the organoaluminum compound, and the treated solid oxide compound, together. This contacting can occur in a variety of ways, such as, for example, blending. Furthermore, each of these compounds can be fed into a reactor separately, or various combinations of these compounds can be contacted together before being further contacted in the reactor, or all three compounds can be contacted together before being introduced into the reactor.
Currently, one method is to first contact the organometal compound and the treated solid oxide compound together, for about 1 minute to about 24 hours, preferably, 1 minute to 1 hour, at a temperature from about 10xc2x0 C. to about 200xc2x0 C., preferably 15xc2x0 C. to 80xc2x0 C., to form a first mixture, and then contact this first mixture with an organoaluminum compound to form the catalyst composition.
Another method is to precontact the organometal compound, the organoaluminum compound, and the treated solid oxide compound before injection into a polymerization reactor for about 1 minute to about 24 hours, preferably, 1 minute to 1 hour, at a temperature from about 10xc2x0 C. to about 200xc2x0 C., preferably 20xc2x0 C. to 80xc2x0 C.
A weight ratio of the organoaluminum compound to the treated solid oxide compound in the catalyst composition ranges from about 5:1 to about 1:1000, preferably, from about 3:1 to about 1:100, and most preferably, from 1:1 to 1:50.
A weight ratio of the treated solid oxide compound to the organometal compound in the catalyst composition ranges from about 10,000:1 to about 1:1, preferably, from about 1000:1 to about 10:1, and most preferably, from 250:1 to 20:1. These ratios are based on the amount of the components combined to give the catalyst composition.
After contacting, the catalyst composition comprises a post-contacted organometal compound, a post-contacted organoaluminum compound, and a post-contacted treated solid oxide compound. Preferably, the post-contacted treated solid oxide compound is the majority, by weight, of the catalyst composition. Often times, specific components of a catalyst are not known, therefore, for this invention, the catalyst composition is described as comprising post-contacted compounds.
A weight ratio of the post-contacted organoaluminum compound to the post-contacted treated solid oxide compound in the catalyst composition ranges from about 5:1 to about 1:1000, preferably, from about 3:1 to about 1:100, and most preferably, from 1:1 to 1:50.
A weight ratio of the post-contacted treated solid oxide compound to the post-contacted organometal compound in the catalyst composition ranges from about 10,000:1 to about 1:1, preferably, from about 1000:1 to about 10:1, and most preferably, from 250:1 to 20:1. These ratios are based on the amount of the components combined to give the catalyst composition.
The catalyst composition of this invention has an activity greater than 100 grams of polymer per gram of treated solid oxide compound per hour, preferably greater than 500, and most preferably greater than about 1,000. This activity is measured under slurry polymerization conditions, using isobutane as the diluent, and with a polymerization temperature of 90xc2x0 C., and an ethylene pressure of 550 psig. The reactor should have substantially no indication of any wall scale, coating or other forms of fouling.
One of the important aspects of this invention is that no aluminoxane needs to be used in order to form the catalyst composition. Aluminoxane is an expensive compound that greatly increases polymer production costs. This also means that no water is needed to help form such aluminoxanes. This is beneficial because water can sometimes kill a polymerization process. Additionally, it should be noted that no fluoro-organo borate compounds need to be used in order to form the catalyst composition. The treated solid oxide compound of this invention is inorganic when the treated solid oxide compound is formed, heterogenous in a organic polymerization medium, and can be can be easily and inexpensively produced because of the substantial absence of any aluminoxane compounds or fluoro-organo borate compounds. It should be noted that organochromium compounds and MgCl2 are not needed in order to form the catalyst composition. Although aluminoxane, fluoro-organo borate compounds, organochromium compounds, and MgCl2 are not needed in the preferred embodiments, these compounds can be used in other embodiments of this invention.
In another embodiment of this invention, a process comprising contacting at least one monomer and the catalyst composition to produce a polymer is provided. The term xe2x80x9cpolymerxe2x80x9d as used in this disclosure includes homopolymers and copolymers. The catalyst composition can be used to polymerize at least one monomer to produce a homopolymer or a copolymer. Usually, homopolymers are comprised of monomer residues, having 2 to about 20 carbon atoms per molecule, preferably 2 to about 10 carbon atoms per molecule. Currently, it is preferred when at least one monomer is selected from the group consisting of ethylene, propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 3-ethyl-1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and mixtures thereof.
When a homopolymer is desired, it is most preferred to polymerize ethylene or propylene. When a copolymer is desired, the copolymer comprises monomer residues and one or more comonomer residues, each having from about 2 to about 20 carbon atoms per molecule. Suitable comonomers include, but are not limited to, aliphatic 1-olefins having from 3 to 20 carbon atoms per molecule, such as, for example, propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, and other olefins and conjugated or nonconjugated diolefins such as 1,3-butadiene, isoprene, piperylene, 2,3-dimethyl-1,3-butadiene, 1,4-pentadiene, 1,7-hexadiene, and other such diolefins and mixtures thereof. When a copolymer is desired, it is preferred to polymerize ethylene and at least one comonomer selected from the group consisting of 1-butene, 1-pentene, 1-hexene, 1-octene, and 1-decene. The amount of comonomer introduced into a reactor zone to produce a copolymer is generally from about 0.01 to about 10 weight percent comonomer based on the total weight of the monomer and comonomer, preferably, about 0.01 to about 5, and most preferably, 0.1 to 4. Alternatively, an amount sufficient to give the above described concentrations, by weight, in the copolymer produced can be used.
Processes that can polymerize at least one monomer to produce a polymer are known in the art, such as, for example, slurry polymerization, gas phase polymerization, and solution polymerization. It is preferred to perform a slurry polymerization in a loop reaction zone. Suitable diluents used in slurry polymerization are well known in the art and include hydrocarbons which are liquid under reaction conditions. The term xe2x80x9cdiluentxe2x80x9d as used in this disclosure does not necessarily mean an inert material; it is possible that a diluent can contribute to polymerization. Suitable hydrocarbons include, but are not limited to, cyclohexane, isobutane, n-butane, propane, n-pentane, isopentane, neopentane, and n-hexane. Furthermore, it is most preferred to use isobutane as the diluent in a slurry polymerization. Examples of such technology can be found in U.S. Pat. Nos. 4,424,341; 4,501,885; 4,613,484; 4,737,280; and 5,597,892; the entire disclosures of which are hereby incorporated by reference.
The catalyst compositions used in this process produce good quality polymer particles without substantially fouling the reactor. When the catalyst composition is to be used in a loop reactor zone under slurry polymerization conditions, it is preferred when the particle size of the solid oxide compound is in the range of about 10 to about 1000 microns, preferably about 25 to about 500 microns, and most preferably, 50 to 200 microns, for best control during polymerization.
In a more specific embodiment of this invention, a process is provided to produce a catalyst composition, the process comprising (optionally, xe2x80x9cconsisting essentially ofxe2x80x9d, or xe2x80x9cconsisting ofxe2x80x9d):
(1) contacting alumina with a solution containing zirconium tetraalkoxide, (Zr(OR)4), where R is an aliphatic radical containing one to twelve carbons, to produce a zirconium-containing alumina having from 1 to 10 weight percent zirconium based on the weight of the zirconium-containing alumina before calcining;
(2) calcining the zirconium-containing alumina at a temperature within a range of 350 to 600xc2x0 C. for 3 to 20 hours to produce a calcined composition;
(3) contacting the calcined composition with carbon tetrachloride in the amount equal to 0.05 to 1 times the weight of the alumina before calcining for 10 minutes to 30 minutes to produce a chlorided, zirconium-containing alumina;
(4) combining the chlorided, zirconium-containing alumina and bis(n-butylcyclopentadienyl) zirconium dichloride at a temperature within a range of 15xc2x0 C. to 80xc2x0 C. for about 1 minute to 1 hour to produce a mixture; and
(5) combining the mixture and triethylaluminum to produce the catalyst composition.
Hydrogen can be used with this invention in a polymerization process to control polymer molecular weight.
A feature of this invention is that the zirconium-containing solid oxide compound is a polymerization catalyst in it""s own right, providing a high molecular weight component onto the usually symmetrical molecular weight distribution of the organometal compound. This component, or skewed molecular weight distribution, imparts higher melt strength and shear response to the polymer than could be obtained from an organometal compound alone. Depending on the relative contributions of the zirconium-containing solid oxide compound and the organometal compound, a bimodal polymer distribution can be obtained.
After the polymers are produced, they can be formed into various articles, such as, for example, household containers and utensils, film products, drums, fuel tanks, pipes, geomembranes, and liners. Various processes can form these articles. Usually, additives and modifiers are added to the polymer in order to provide desired effects. It is believed that by using the invention described herein, articles can be produced at a lower cost, while maintaining most, if not all, of the unique properties of polymers produced with metallocene catalysts.